The Japanese obsession with quality and precision resulted in an ideal-cut diamond cut so exactly that the shadows of facets are arranged in curious kaleidoscopic patterns.
The Hearts and Arrows diamonds are rounds cut so precisely that they show a specific pattern through the “Idealscope” gizmo. The pattern resembles arrows radiating from the center, hence the name. Viewed from the pavilion, the pattern resembles eight naked people looking for soap under the round table. Japanese called it “hearts.”
The idea for Idealscope was “borrowed” from Professor Okuda’s Fire Scope™ created in the 1970′s. Japan is the birthplace of the Hearts & Arrows brand, the term patented by Mr. Kinsaku Yamashita. The Central Grading Laboratory (CGL), the largest gem lab in Japan, patented Heart & Cupid trade name used by many Japanese companies to compete with Hearts & Arrows. The original Swords & Shields was replaced by the sugary “Hearts and Arrows.”
All GIA ideal-cut diamonds display symmetric patterns, but Hearts & Arrows is considered a premium and the most recognized brand.
Observing H&A diamonds
A small plastic gizmo sold on eBay or Alibaba is used to observe the pattern of eight pointy arrows. Eight hearts are visible when the stone is flipped upside down.
To use an Ideal Scope, one needs to position the diamond in a slotted disc that comes with it and look through the magnifying glass directly at the diamond.
Definition of H&A diamond
The pavilion’s eight main facets and the sixteen lower halves are responsible for the well-defined H&A arrow pattern. The optimum lower half length should be 75% to 80%, with 76-77% being optimal, all the same length and angle. The ideal range for the Star facets on the crown is 42% to 58%, with 45%-50% being the optimum.
All Ideal cut diamonds with GIA Excellent cut grade show a radiating pattern when viewed with IdealScope. 40.6 to 41-degree pavilion angle guarantees the diamond is Heart and Arrow.